The invention relates generally to lasers and more particularly to lasers for generating a beam with its frequency equal to the sum of the frequencies of two pumping beams.
The development of pulsed lasers has provided beams with peak powers in the megawatt to gigawatt range. These beams have been used to study the non-linear response of molecules to high optical fields. Recently, much interest has centered on using these interactions to design parametric lasers that generate coherent beams at harmonic and sum and difference frequencies. However, these parametric lasers have met with limited success due to the dependence of non-linear interaction on the third order susceptibility term .chi..sup.(3). Since this term is generally small, the non-linear reaction has a very high threshold thereby requiring pumping beams of high power.